Stirling cycle engine power control means

ABSTRACT

To control the power of a hot gas Stirling cycle engine a dead volume chamber is connected with the low temperature working chamber by two valves. The first valve has a smaller opening thereby operating the engine to absorb power acting as a brake. The second valve has a larger opening which permits the engine to idle at reduced power.

Unlted States Patent [1 1 [111 3,811,272 Hakansson May 21, 1974 [54]STIRLING CYCLE ENGINE POWER 2,602,288 7/1952 Rinia et al. 60/24 CONTROLA S 2,607,190 8/1952 2,61 L237 9/1952 [75] Inventor: Sven Anders SamuelHakansson, 2317.950 12 1957 Malmo, Sweden 3,600,886 8/1971 .laspers etal. 60/24 [73] Assignee: Kommanditbolaget United Stirling (Sweden) ABMalmo, v Primary Examiner-Edgar W. Geoghegan Sweden AssistantExaminer-H. Burks, Sr. I 221 Filed; 9, 1972 Attorney, Agent, orFirmLaurence R. Brown, Esq. [21] App]. No.: 305,074

[30] Foreign Application Priority Data [57] ABSTRAT NOV. 9, 197' GreatBritain I. 5l865/7l To control the power of a hot ga y le ngi e a deadvolume chamber is connected with the low [52] US. Cl. 60/518 temperatureki Chamber by two valves The first Clvalve has a maller openingoperating -the ene Fleld of Search gine to absorb power acting as abrake econd V valve has a larger opening which permits the engine to[56] References cued I idle at reduced power.

UNITED STATES PATENTS 987,938 3/1911 Anderson 60/24 ux 5 Claims, 3Drawing Figures PATENTEDHAY 21 197 2 3,8 1.1, 272

SHEET 1 BF 2 Fig.1

PATENTEBma 1 m4 SHEET 2 0? 2 STIRLING CYCLE ENGINE POWER CONTROL MEANSvThis invention relates to a hot gas engine of the kind (hereincalled.the kind defined") comprising a variable volume first workingchamber connected through a regenerator to a variable volume secondworking chamber, the first working chamber containing working gas at atemperature higher than that of the gas in the second working chamber,and one of said chambers being connected to a control chamber'throughcontrollable passage means, that is to say passage means which can beselectively fully open or fully closed or regulated to allow restrictedflow of gas.

If connected to one of the working chambers the said control chamberwill act as a dead volume and will cause a decrease in the engine poweroutput. Therefore, it is convenient to govern the power output of a hotgas engine by connectinga working chamber selectively to one or moredead volume chambers of different sizes.

However, it has hitherto been considered necessary to use very largedead volume chambers if a decrease in engine power output down to idlingis to be obtained solely by such means.

The present invention is therefore intended to provide a hot gas engineof the kind defined in which a dead volume power output control ofmoderate size may serve effectively as the only power output controlmeans.

According to the invention there is provided a hot gas engine of thekind defined characterised in that the said controllable passage meanscomprises two or more parallel connections each of which iscontrollable.

The scope of the monopoly sought is defined in the claims hereinafter,and how the invention may be put into practice is described in moredetail with reference to the accompanying drawings, in which FIG. 1schematically shows a hot gas engine according to the invention,

FIG. 2 shows a diagram illustrating the variations in the power outputof a hot gas engine in dependence upon the opening of passage meansbetween an engine working chamber and a dead volume" chamber of constantvolume, and

FIG. 3 shows a vertical section through parts of a secnd hot gas engineaccording to'the invention. 7

The hot gas engine shown schematically .in FIG. 1 is of thesingle-acting type comprising a cylinder 1 with two pistons 2 and 3. Theengine contains working gas in a high temperature working chamber 4 andin a lowtemperature working chamber 5. The two chambers 4 and 5 areinterconnected through a passage containing a regenerator 6 and a cooler7. A heater 8 maintains the temperature of the high temperature workingchamber 4.

The low temperature working chamber 5 is connected to a control chamber9 of constant volume. The chamber 9 is a dead volume chamber and isconnected to the chamber 5 through passage means comprising two parallelconnections 10' and l 1, each being controllable by a valve 12 and 13respectively.

The two pistons 2 and 3 are provided with piston rods 14 and 15 which inturn are connected to a drive. mechanism (not shown) so that themovements of the piston 2 are 90 degrees in advance of the movements ofthe piston 3.

The engine illustrated in FIG. 1-will operate as follows:

Assume that the engine is running at constant temperatures in the highand low temperature working chambers 4 and Sand at a constant meanpressure of the working gas. Initially the valves 12 and 13 are closedto shut off completely the connections 10 and 11 to the dead volumecontrol chamber 9. The engine is now running at an output powercorresponding to the value A in the diagram of FIG. 2, in which theordinates represent the engine power output values while the abscissaerepresent the extent of the opening of the connections l0 and 11.

From FIG. 2 it will be understood that openingof the connections 10 and11 to a small extent will immediately cause a substantial decrease inthe engine power output down to a value B, which in the case illustratedis negative, i.e., the engine absorbs power from a flywheel or othermoving parts and theload and acts as a brake. A further opening of thepassages 10 and 11 will cause an increase in power output to a value Cwhich may be for example 40 percent of the value A. The two connections10 and 11 may be designed so that full opening of the valve 12 only willcause the engine output to reach the value B, while full opening of thevalve 13 only will. cause the engine output to reach the value C. I

FIG. 3 shows in vertical section a double-acting hot gas enginecomprising a cylinder 20having a single piston 21 mounted'forreciprocating therein. The piston 21 is provided with a piston rod 22secured to a crosshead 23 with a connection rod 24 journalled on acrank-shaft 25 in conventional manner.

The piston 21 separates a high temperature working chamber 26 from a lowtemperature working chamber 27. The high temperature working chamber 26is connected to a system of pipes 28.arranged to be heated by heatdeveloped in a combustion chamber 29.

Through a channel 30 the low. temperature working chamber 27 isconnected to a cooler 31 and a regenerator 32, which in turn isconnected to a pipe system 33 similar in type to the pipe system 28.

It will be understood that in a four-cylinder doubleacting hot gasengine the cranks of the crank-shaft 25 may be displaced relative to'each other, and the ar-' rangement may be such that an expansion of thehigh temperature working'chamber 26 may be effected 90 in advance of anexpansionof the respective low temperature working chamber 27. Thus theworking cycle of the engine of FIG. 3 is substantially the same as thatof the engine shown in FIG. 1.

The channel 30 may communicate with a dead volume chamber 34 throughopenings governed by two valve members 35 and 36 respectively. The saidvalve members are in the form of pistons arranged movably in cylinders37 and 38 respectively. The valve member 35 governs a smaller openingwhich when open whilst the other valve is closed will cause the engineto act as a brake. The piston 36 governs a larger opening which whenopen whilst the other valve is closed will cause a reduction inengineoutput whilst maintaining a moderately high degree of efficiency.

The valve members 35 and 36 may be governed by working gas of either thehighest or the lowest working gas cycle pressure fed to the interior ofthe cylinders 37 and 38 through pipes 39 and 40..

The dead volume control chamber 34 may be connected to a further deadvolume control chamber 41 by an opening governed by a valve 42. Theeffect of thus adding the chamber 41 to the chamber 34 will be todecrease the engine output to a greater extent when the valve 36 isopened.

For simplicity in construction and operation it is preferred to provideonly two parallel controllable connections between a working chamber anda dead volume chamber, the control means being such that each of thesaid connections can merely be selectivelyfully open or fully closed,but it will be appreciated that it is possible to provide one or morefurther controllable connections in parallel with the said twoconnections and that the connections may be provided with valves orother control means which allow regulation of the gas flow therein.

What we claim is:

1. Power control means for a hot gas engine having high temperature andlow temperature working chambers, comprising in-combination, a deadvolume control chamber, at least two passageways from said lowtemperature working chamber to said =dead volume control chambertocontrol the size ofopening into said chamber from saidlow temperatureworkingchamber at a set of valves representing predetermined lowerengine output'pow'er levels, at least one valve of which providesbraking by the engine thereby absorbing energy from a load connectedthereto, and independently operable valve means for selectively openingand closing each of said passageways separately thereby establishingsaid predetermined engine output power levels.

2. Power control means as defined in claim 1, wherein the size of saidpassageways is different to offer different resistance to gas flowtherethrough.

3. Power control means as defined in claim 2,-

wherein the size of said passageways is selected so that when thesmaller passageway only is opened the engine will absorb power and actas a brake, and when the 5. Power control means as defined in claim 1,includ" ing a second dead volume chamber, a passageway between the twodead volume chambers and selectively operable valve means opening andclosing said latter passageway. 1 1 I

1. Power control means for a hot gas engine having high temperature andlow temperature working chambers, comprising in combination, a deadvolume control chamber, at least two passageways from said lowtemperature working chamber to said dead volume control chamber tocontrol the size of opening into said chamber from said low temperatureworking chamber at a set of valves representing predetermined lowerengine output power levels, at least one valve of which provides brakingby the engine thereby absorbing energy from a load connected thereto,and independently operable valve means for selectively opening andclosing each of said passageways separately thereby establishing saidpredetermined engine output power levels.
 2. Power control means asdefined in claim 1, wherein the size of said passageways is different tooffer different resistance to gas flow therethrough.
 3. Power controlmeans as defined in claim 2, wherein the size of said passageways isselected so that when the smaller passageway only is opened the enginewill absorb power and act as a brake, and when the larger passageway isopened the engine will run at reduced power.
 4. Power control means asdefined in claim 1, wherein each valve means comprises a piston member,and means for controlling said piston members to open and close saidpassageways with gas pressure corresponding respectively to the lowestand highest working gas pressures of said engine.
 5. Power control meansas defined in claim 1, including a second dead volume chamber, apassageway between the two dead volume chambers and selectively operablevalve means opening and closing said latter passageway.